Recently a kohai (one of those very serious martial arts students who asks lots of questions, and really cares about the answers) asked me, 'So, do you train at full speed all the time?'
My immediate answer, of course, was, "No," but it made me think for a couple of days about it. The full answer that I finally gave was that I spend probably 80% (+/- 10) of my time training at a jogging pace, 10-20% of my time training at a running pace, and maybe 2% or less at 'full speed' - say, sprinting speed, as fast as you can go - and that only during tests and/or when I or my partner are out of control.

How does this work out for you guys? I imagine that there are plenty of people (some in my own dojo) whose 'running' percentage is higher, but what do you consider 'full speed' and how much training do you do there?